The present invention relates to an apparatus for transporting sheet-like products, in particular printed products such as magazines and newspapers by means of a system of conveyor belts and controllable grippers.
An apparatus for conveying printed products is disclosed in U.S. Pat. No. 3,955,667 and corresponding Swiss Patent CH-A-592 562 to Erwin Muller. The printed products are fed in imbricated formation on a first conveyor belt to a takeover region where rotating grippers on a second conveyor belt take the printed products and transport them further. The first conveyor belt is of a rocker-like design and is prestressed in the upward direction by means of a spring.
The grippers on the second conveyor belt rotate at a speed that corresponds to the speed of the first conveyor belt, and the space between each gripper on the second conveyor belt corresponds to the spacing of the leading edges of the printed products. Each gripper comprises a fixed upper clamping jaw and a lower movable clamping jaw or tongue which is arranged on a shank and rotates both towards and away from the upper clamping jaw.
When the clamp is in the open position, the shank is extended toward the first conveyor belt and is swiveled about its longitudinal axis, so that the movable clamping tongue is directed at right angles to the rotating direction and to the fixed clamping jaw. The free end of the shank of each gripper bears on the upper side of a printed product and ahead of the leading edge of the following printing product. To seize a printed product, the shank is swiveled and the movable clamping tongue engages the printed product from underneath at its leading edge. The upward displacement of the shank causes the clamping jaw to close, and the printed product is then clamped at its leading edge between the fixed clamping jaw and the movable clamping jaw.
U.S. Pat. No. 3,671,035 and corresponding Swiss Patent CH-A-468923 to Walter Reist disclose an apparatus for transporting printed products such as newspapers in imbricated formation by means of a belt conveyor with grippers. The imbricated printed products are conveyed from a printing room on a first belt conveyor to a second takeover belt conveyor having grippers arranged on the conveyor that runs at an angle past the first belt conveyor. The grippers are arranged such that there are two parallel rows of grippers on each side of the conveyor. The grippers on the second takeover conveyor have a fixed clamping jaw and a movable clamping jaw arranged on a shank which can be turned and displaced in a longitudinal direction.
At the point the printed products are transferred from the first conveyor to the second takeover conveyor, the printed products bend as a result of the angle between the two belt conveyors. The bend in the printed products causes the underlying trailing edge of the printed product to be exposed and rest on the fixed clamping jaw. The movable clamping jaw is then rotated such that it is positioned above the fixed clamping jaw and the printed product is then clamped between the two clamping jaws.
U.S. Pat. No. 4,905,986 and corresponding European Patent No. A-0 300 171 to Erwin Muller also disclose an apparatus with grippers for conveying imbricated printed products. The printed products are feed in imbricated formation onto a belt conveyor having grippers such that the leading edge of each printed product is covered by the one in front of it.
The grippers on the belt conveyor are individually controllable and are separated by a distance corresponding to the distance between the leading edges of the printed products. The grippers have a fixed clamping jaw and a movable clamping jaw. The fixed clamping jaw of the gripper rests against the bottom of the printed product to be seized at the leading edge.
In order to seize a printed product at its covered leading edge, the movable clamping jaw raises the leading edge of the printed product covering the product to be seized which allows the movable clamping jaw to clamp the desired printed product between the movable clamping jaw and the fixed clamping jaw.
Another apparatus used to convey printed products is disclosed in U.S. Pat. No. 4,201,286 and corresponding Swiss Patent CH-A-618 398 to Jacques Meier. The imbricated printed products are conveyed from a printing room on a first belt conveyor to a second takeover belt conveyor which runs at an angle past the first belt conveyor. The takeover conveyor has individually controllable clamps and revolves continuously in a horizontal direction above the end of the upwardly moving first belt conveyor. The takeover conveyor has a takeover region with a transfer wheel which in each case releases a clamp whenever the leading edge of a printed product has been introduced by the first belt conveyor into the open clamp.
Therefore, a primary object of the present invention is to provide an apparatus for transporting sheet-like products which allows the products to be seized at their trailing edge by a conveyor having grippers at a high processing speed irrespective of the position of the conveyor feeding the printed products.